prescript

# VS Code JavaScript IntelliSense and/or TypeScript Support

Out of the box, prescript comes with a type declaration file. This means it will work with VS Code IntelliSense for JavaScript right away, even if you are using just JavaScript.

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# Writing tests in TypeScript

If you want to write tests in TypeScript, you can configure prescript to inject ts-node into the Node.js runtime. This will let you write tests in TypeScript.

  1. Install ts-node.

  2. Create prescript.config.js with this contents:

    require('ts-node/register/transpile-only')

# Declaring the type of prescript state

The type of state variable, passed to your action functions in action() and defer() APIs defaults to an unknown type.

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That means that by default you don’t get autocompletion when writing actions:

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To fix this, you can define the type of your prescript state by following these steps:

  1. If you are not using TypeScript, set up a JavaScript project in VS Code by creating a jsconfig.json file at the root of your project.

    {
  "compilerOptions": { "target": "ES6" },
  "include": ["tests"],
  "exclude": ["node_modules", "**/node_modules/*"]
}

    Reload VS Code after creating this file to make sure that VS Code picks up the configuration file.

  2. Create a file state.d.ts which will contain the type definition of your state. It should declare an interface GlobalState in a global namespace Prescript, thus triggering declaration merging. Here’s an example:

    import * as puppeteer from 'puppeteer'

declare global {
  namespace Prescript {
    interface GlobalState {
      browser: puppeteer.Browser
      page: puppeteer.Page
    }
  }
}

export {}

    Anything you add to the GlobalState interface inside Prescript namespace will show up in the type of the state variable.

  3. Now you have IntelliSense for your test state!

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